In bottling, canning, and other industries large amounts of packaging material such as folded, flat, paperboard containers must be handled. Typically, packaging material arrives in shipping containers such as corrugated cardboard boxes. The boxes are shipped on pallets and it is necessary to remove the packaging material from the corrugated boxes on the pallets to automated processing lines where, for example, folded paperboard containers are opened, filled with beverage cans, and then sealed.
In most instances, the task of removing the packaging material is carried out manually. Manual labor is used to perform this task because humans (as opposed to most existing machines) are able to handle packaging material without damaging it. This is important because while packaging material serves a functional purpose as a product container, it must also be aesthetically attractive and visually appealing. Often containers made from packaging material have elaborate printing on their surfaces and filled containers are stacked to create aisle displays in supermarkets and other retail stores. Further, the paperboard containers may also be used as product dispensers, such as, for example, facial tissue boxes. Thus, it is of great importance that paperboard containers or similar items be handled without damaging them or the printing or other indicia on their surfaces.
While having certain advantages, manually handling shipping containers and unloading paperboard containers is relatively strenuous and tedious. It can literally be "back-breaking work," as the continued lifting and moving of packaging material can cause back injuries. Further, many workers must be employed to remove the folded paperboard containers from their boxes and feed the folded containers into processing lines.
In an effort to reduce salary and injury costs, there have been some attempts to automate this process by using robots. As in known in the art, industrial robots may be fitted with various claws and other grasping devices to pick up and move articles of interest. In some known systems, a first robot with a grasping device is used to remove a single shipping container containing folded paperboard containers from its pallet to an unloading station. At the unloading station, a second robot having a mechanical gripper is used to remove the folded paperboard containers from the shipping container. While functional, most known systems are not satisfactory because two robots are needed. This requirement increases the cost of an automated system. Further, mechanically grasping and contacting of paperboard containers causes them to be scratched, marked, or otherwise marred or damaged while they are handled.
In later systems, such as the one shown in U.S. application Ser. No. 08/571,215 (now U.S. Pat. No. 5,727,832), only a single robot is used. The robot is fitted with an end-effector which has two grippers, one for handling boxes filled with folded paperboard containers and another for handling the paperboard containers themselves. However, this end-effector is relatively large and the gripper used to handle full boxes cannot easily remove boxes from a tightly-packed pallet. Further, the end-effector has no capability to remove dunnage sheets placed between layers of boxes in a pallet, necessitating manual removal of the sheets.
Accordingly, there is a need for a device which may be used to handle stacks of boxes or other containers containing relatively flat articles. More specifically, there is a need for a device which can remove boxes or other shipping containers from a tightly packed pallet to an unloading station or location, remove the flattened articles from the shipping container without damaging them, handle any dunnage which may be placed in the pallet, and be relatively small and lightweight so that is can operate in a limited amount of space and at relatively high speeds.